In elevator design, progressive safety gears serve to stop uncontrolled movement states of the elevator car and namely the falling or runaway motion of the elevator car as quickly as possible by bringing the elevator car to a standstill by the shortest possible route, i.e. by “catching” it—so that nothing happens, even if the elevator car is fully loaded and falls or runs away in the vicinity of the shaft pit or shaft head.
A wide variety of progressive safety gears are known. Most progressive safety gears use the principle of self-locking. After the progressive safety gear is triggered, at least one mobile brake block (i.e. an element that directly embodies the brake lining itself or that is connected to a brake lining) is pulled into a wedge-shaped gap, which is usually elastically delimited at one end by a spring element, until it reaches a position in which the maximum permissible brake force is generated.
In recent times, hydraulically actuated progressive safety gears have also been used.
All of these progressive safety gears share the common trait that during the catching operation, very high pressures occur between the brake linings and the guide rails that are assigned to them as “braking rails.”
As a result, the brake linings are put under a great deal of stress during the catching operation. Because of this, for the past 50 years and more, steel brake blocks or brake blocks with a steel lining have been used, whose surface that comes into contact with the guide rail is hardened or tempered in order to reduce the wear on the brake block or its brake lining.
It is not uncommon, however, even during the first catching operation, for the influence of the high pressure and the resulting frictional heat to cause instantaneous local cold welding with a subsequent re-separation between the steel surfaces of the brake block or its brake lining and the guide rail. As a result, even after a small number of catching operations, the brake block and/or its brake lining are so severely damaged on their surface provided for coming into contact with the guide rail that they have to be replaced.
The object of the invention, by contrast, is to disclose an elevator with a wear-resistant progressive safety gear.